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Graphene-based materials (GBMs) have been increasingly explored for biomedical applications. However, interaction between GBMs-integrating surfaces and bacteria, mammalian cells, and blood components, that is, the major biological systems in our body, is still poorly understood. In this study, we systematically explore the features of GBMs that most strongly impact the interactions of GBMs films with plasma proteins and biological systems. Films produced by vacuum filtration of GBMs with different oxidation degree and thickness depict different surface features: graphene oxide (GO) and fewlayer GO (FLGO) films are more oxidized, smoother, and hydrophilic, while reduced GO (rGO) and few-layer graphene (FLG) are less or nonoxidized, rougher, and more hydrophobic. All films promote glutathione oxidation, although in a lower extent by rGO, indicating their potential to induce oxidative stress in biological systems. Human plasma proteins, which mediate most of the biological interactions, adsorb less to oxidized films than to rGO and FLG. Similarly, clinically relevant bacteria, Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, adhere less to GO and FLGO films, while rGO and FLG favor bacterial adhesion and viability. Surface features caused by the oxidation degree and thickness of the GBMs powders within the films have less influence toward human foreskin fibroblasts; all materials allow cell adhesion, proliferation and viability up to 14 days, despite less on rGO surfaces. Blood cells adhere to all films, with higher numbers in less or nonoxidized surfaces, despite none having caused hemolysis (<5%). Unlike thickness, oxidation degree of GBMs platelets strongly impact surface morphology/ topography/chemistry of the films, consequently affecting protein adsorption and thus bacteria, fibroblasts and blood cells response. Overall, this study provides useful guidelines regarding the choice of the GBMs to use in the development of surfaces for an envisioned application. Oxidized materials appear as the most promising for biomedical applications that require low bacterial adhesion without being cytotoxic to mammalian cells.

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Thrombosis and infection are the leading causes of blood-contacting devices (BCD) failure, mainly due to existing biomaterials' poor performance. Poly(2-hydroxyethyl methacrylate) (pHEMA) has excellent hemocompatibility, but the weak mechanical properties...

Gastric infections are mainly caused by Helicobacter pylori (H. pylori), a bacterium that colonizes the gastric mucosa of over 50% of the world's population. Chronic H. pylori infection has been associated with gastric diseases such as chronic gastritis, peptic ulcer and gastric adenocarcinoma. Current eradication treatment relies on antibiotic-based therapies that are unsuccessful in approximately 20% of the patients. Chitosan, a natural and cationic polysaccharide has been investigated in the treatment of H. pylori infection. Due to its mucoadhesive properties, it has been used in the form of micro/nanoparticles, polyelectrolyte complexes or coatings as antibiotic encapsulation systems for gastric delivery, but alternative molecules may also be incorporated. It has been recently proposed that chitosan can also be used for H. pylori binding and scavenging from the host stomach due to its antimicrobial/binding properties. In this manuscript, a brief description of the use of chitosan in H. pylori treatment is reviewed.

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